1. Field of the Invention
This invention relates to electrochemical cells. More particularly, this invention relates to electrochemical cells for use in thermal batteries. In particular, this invention relates to thermal battery cells employing calcium anodes and oxidizing molten nitrate and perchlorate salts.
2. Description of the Prior Art
Calcium anodes have been used with molten nitrate electrolytes in thermal battery cells to obtain high voltage outputs. A problem with this combination has been flashing. Flashing refers to the rapid, self-sustaining reaction of depassivated calcium with nitrate, yielding a flash of light. This problem was avoided in U.S. Pat. No. 4,184,018 by the use of a non-flashing electrolyte containing potassium, nitrate and chloride ions. When thermal battery cells containing lithium perchlorate and lithium nitrate were scaled up in size, the problem of the calcium anode flashing or deflagrating returned.
Previous thermal battery systems have utilized homogeneous mixtures as the electrolyte. The use of additives to the electrolyte has been found to improve performance of the cathode and the anode. U.S. Pat. No. 4,190,704 describes the use of chloride ion to improve the calcium anode performance. AgNO.sub.3 has been used as an additive to improve cathode performance and allow a higher current density. The use of homogeneous mixtures has not effectively utilized the additives in increasing power density.